This invention relates to remote signalling systems for use with in-house telephone systems and more particularly is concerned with a data signalling system that may be connected to operate through a PABX system without need for any modifications to any of the existing equipment.
Numerous applications for remote signalling systems are found in connection with the conventional in-house telephone systems that are used in motels, hotels, hospitals and the like. Such systems typically include a plurality of area or room telephones each being either of the conventional rotary dial or tone dial signalling type and each having a separate telephone line, a plurality of trunk lines, and a central telephone switching unit such as a PABX system operable to selectively control connection between the telephone lines and the trunk lines.
Various types of signalling systems for indicating room status have been proposed for motel and hotel use, for example: See U.S. Pat. Nos., 3,614,325; 3,742,141; 3,777,065; 3,854,009; and 3,892,922. Such systems are complex and require various modifications to the conventional telephone system which in general are unduly expensive. In addition, these systems require access to the telephone lines of each room and seriously lack versatility and flexibility.
While there is general agreement as to the value of remote signalling systems in conjunction with in-house telephone systems, the marketing needs have not been met because of the above mentioned drawbacks to the prior systems.